I just spent some time poking through hatchery websites.... Your bird doesn't quite fit any photo/description I can find.
--Black Jersey Giant: should have single comb, yours looks like rose comb.
--Black Australorp: should have single comb, yours looks like rose comb.
--Black Wyandotte: should have yellow legs/feet, yours has dark ones. (But a dark-legged bird could come from yellow-legged parents, so this is a possibility. Comb type is right.)
--Black Hamburg: should be a small breed, with white earlobes. I can't be sure about size on yours, but I don't think I see white earlobes.
--Black Rosecomb Bantam: should be very small, with white earlobes. As above, not sure about size and earlobes.
--Easter Egger/Ameraucana: could certainly be that color, but has a pea comb, while yours appears to have a rose comb. Would also probably have a puffy face (muff/beard), which yours lacks.
Do you know which hatchery Tractor Supply Company got their chicks from? If so, you could look through their list of breeds--maybe I'm missing something obvious.
My best guess would be Black Rosecomb or Black Hamburg, possibly with "wrong" earlobe color (if a hatchery sells Blue Hamburgs, some will really be Black, because of how the genetics work.)